1. Field of the Invention
The present invention relates to a catadioptric projection optical system suitable for applications to projection optical systems for 1.1 or demagnifying projection in projection exposure apparatus such as steppers used in fabricating, for example, semiconductor devices or liquid crystal display devices, etc., by photolithography process. More particularly, the invention relates to a catadioptric projection optical system of a magnification of 1/4 to 1/5 with a resolution of submicron order in the ultraviolet wavelength region, using a reflecting system as an element in the optical system.
2. Related Background Art
In fabricating semiconductor devices or liquid crystal display devices, etc by photolithography process, the projection exposure apparatus is used for demagnifying through a projection optical system a pattern image on a reticle (or photomask, etc.) for example at a ratio of about 1/4 to 1/5 to effect exposure of the image on a wafer (or glass plate, etc.) coated with a photoresist or the like.
The projection exposure apparatus with a catadioptric projection optical system is disclosed, for example, in Japanese Laid-open Patent Application No. 2-66510, Japanese Laid-open Patent Application No. 3-282527, U.S. Pat. (USP) No. 5,089,913, Japanese Laid-open Patent Application No. 5-72478, or U.S. Pat. No. 5,052,763, No. 4,779,966, No. 4,65,77, No 4,701,035.